Test Accuracy of the Korean version of the Informant Questionnaire on Cognitive decline in the elderly for detecting Post-stroke Dementia

A study of the Korean version of the Vascular Cognitive Impairment Harmonization Standards (K-VCIHS) in a multicenter, hospital-based stroke cohort in Korea has already been completed. We studied the test accuracy of the Korean version of the Informant Questionnaire on Cognitive Decline in the Elderly (K-IQCODE) as a screening tool for post-stroke dementia (PSD) in this cohort.

Methods and Findings:

Cognitive status was evaluated using the K-IQCODE as a screening tool and the 60-minute K-VCIHS-neuropsychological (NP) test protocol as a diagnostic standard of PSD at 3 months post-stroke. We compared the concordance rate for PSD diagnoses by the K-IQCODE and DSM-IV criteria from 60-minute K-VCIHS-NP test protocols for patients involved in the K-VCIHS study. Concordance between the PSD results from K-VCIHS-NP test protocols and the K-IQCODE was 45.3% (Kappa value = 0.471, p < 0.001). With a cut-off point of 3.6+ on the K-IQCODE for Alzheimer’s disease, the ROC curve showed a sensitivity of 45%, specificity of 96%, and area under the receiver operating characteristic of 0.784.

Conclusion:

The IQCODE was not suitable for screening PSD at 3 months post-stroke because of its low sensitivity around the cut-off point for AD. We investigated other suggested optimal cut-off points on the IQCODE for PSD, but found that these were also unsuitable.